No abstract

Peptide KEDW (Lys-Glu-Asp-Trp-NH2) is known to reduce the blood glucose level in rats with streptozotocin-and alloxan-induced diabetes mellitus. Here, we examine the influence of KEDW peptide on cell differentiation and DNA structure. KEDW peptide increased the expression of PDX1, NGN3, PAX6, FOXA2, NKX2-2, NKX6.1, and PAX4 genes but decreased MNX1 and HOXA3 gene expression when added to pancreatic cell culture. Moreover, KEDW peptide caused an increase in expression of PDX1, NGN3, PAX6, FOXA2, NKX2-2, NKX6.1, and PAX4 proteins without affecting synthesis of MNX1 and HOXA3 when added to pancreatic cell culture. Results obtained through physical methods (UV-visible absorption, circular dichroism) and molecular modelling methods suggest that the peptide binds to DNA along the major groove. Experimental and theoretical data provided a 3D model of the stable DNA-peptide complex. We propose that regulation of differentiation factor expression in pancreatic (endocrine) cells by KEDW peptide occurs through specific binding of the peptide to regulatory elements of corresponding genes.

Analysis of the main parameters of molecular mechanics (number of hydrogen bonds, hydrophobic and electrostatic interactions, DNA-peptide complex minimization energy) provided the data to validate the previously proposed qualitative models of peptide-DNA interactions and to evaluate their quantitative characteristics. Based on these estimations, a three-dimensional model of Lys-Glu and Ala-Glu-Asp-Gly peptide interactions with DNA sites (GCAG and ATTTC) located in the promoter zones of genes encoding CD5, IL-2, MMP2, and Tram1 signal molecules.

No abstract

No abstract